I have never had to write one, but I would think this is where honesty plays an important role. I am sure others with more sponsoring experience will come along with sage advice.
I just saw that you recently joined and no one had chimed in yet, so wanted to respond.
I do know that if someone is serious about their problem and not just going through the motions due to legal consequences that that individual's progress on Step 1 could probably be explained to the judge.
I wouldn't reveal details about what brought the sponsee to accept Step 1, but focus on his or her acceptance of the problem. That basically was the epiphany on my first step, total acceptance of the problem and total surrender that I was beaten and left with no other options other than doing Steps 2 through 12.